JPWO2010087518A1 - Epitaxial silicon carbide single crystal substrate and manufacturing method thereof - Google Patents
Epitaxial silicon carbide single crystal substrate and manufacturing method thereof Download PDFInfo
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- 239000000758 substrate Substances 0.000 title claims abstract description 172
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 140
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 139
- 239000013078 crystal Substances 0.000 title claims abstract description 104
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- 238000000034 method Methods 0.000 claims abstract description 46
- 230000003746 surface roughness Effects 0.000 claims abstract description 45
- 239000010409 thin film Substances 0.000 claims abstract description 32
- 239000007789 gas Substances 0.000 claims description 87
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 72
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims description 72
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims description 72
- 239000000460 chlorine Substances 0.000 claims description 30
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 13
- 229910052710 silicon Inorganic materials 0.000 claims description 13
- 238000002230 thermal chemical vapour deposition Methods 0.000 claims description 13
- 239000010703 silicon Substances 0.000 claims description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 9
- 229910052799 carbon Inorganic materials 0.000 claims description 9
- 125000001309 chloro group Chemical group Cl* 0.000 claims description 5
- 239000010408 film Substances 0.000 abstract description 94
- 230000004888 barrier function Effects 0.000 description 17
- 230000000694 effects Effects 0.000 description 16
- 239000010410 layer Substances 0.000 description 14
- 238000005530 etching Methods 0.000 description 12
- 230000007547 defect Effects 0.000 description 11
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 125000004429 atom Chemical group 0.000 description 6
- 230000015556 catabolic process Effects 0.000 description 6
- 238000007796 conventional method Methods 0.000 description 6
- 238000000879 optical micrograph Methods 0.000 description 6
- 239000002994 raw material Substances 0.000 description 5
- 238000000089 atomic force micrograph Methods 0.000 description 4
- 238000005229 chemical vapour deposition Methods 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 235000019592 roughness Nutrition 0.000 description 2
- 239000011856 silicon-based particle Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 239000006061 abrasive grain Substances 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
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- 230000007423 decrease Effects 0.000 description 1
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- 238000011982 device technology Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
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- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 description 1
- 239000005052 trichlorosilane Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
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- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
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- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
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- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
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Abstract
本発明は、オフ角度が６°乃至それ以下の基板を用いたエピタキシャル成長において、ステップ−バンチングの発生を抑えた高品質エピタキシャル膜を有するエピタキシャルＳｉＣ単結晶基板、及びその製造方法を提供するものである。オフ角度が６°以下である炭化珪素単結晶基板上に炭化珪素単結晶薄膜を形成したエピタキシャル炭化珪素単結晶基板であって、前記炭化珪素単結晶薄膜表面の表面粗さ（Ｒａ値）が０．５ｎｍ以下であることを特徴とするエピタキシャル炭化珪素単結晶基板エピタキシャル炭化珪素単結晶基板、及びその製造方法である。The present invention provides an epitaxial SiC single crystal substrate having a high-quality epitaxial film in which generation of step-bunching is suppressed in epitaxial growth using a substrate having an off angle of 6 ° or less, and a method for manufacturing the same. . An epitaxial silicon carbide single crystal substrate in which a silicon carbide single crystal thin film is formed on a silicon carbide single crystal substrate having an off angle of 6 ° or less, and the surface roughness (Ra value) of the silicon carbide single crystal thin film surface is 0 An epitaxial silicon carbide single crystal substrate characterized in that the thickness is 1.5 nm or less, and a method for manufacturing the same.
Description
本発明は、エピタキシャル炭化珪素（ＳｉＣ）単結晶基板及びその製造方法に関するものである。 The present invention relates to an epitaxial silicon carbide (SiC) single crystal substrate and a method for manufacturing the same.
炭化珪素（ＳｉＣ）は、耐熱性及び機械的強度に優れ、物理的、化学的に安定なことから、耐環境性半導体材料として注目されている。また、近年、高周波高耐圧電子デバイス等の基板としてＳｉＣ単結晶基板の需要が高まっている。 Silicon carbide (SiC) has attracted attention as an environmentally resistant semiconductor material because it is excellent in heat resistance and mechanical strength and is physically and chemically stable. In recent years, the demand for SiC single crystal substrates as substrates for high-frequency, high-voltage electronic devices has increased.
ＳｉＣ単結晶基板を用いて、電力デバイス、高周波デバイス等を作製する場合には、通常、基板上に熱ＣＶＤ法（熱化学蒸着法）と呼ばれる方法を用いてＳｉＣ薄膜をエピタキシャル成長させたり、イオン注入法により直接ドーパントを打ち込んだりするのが一般的であるが、後者の場合には、注入後に高温でのアニールが必要となるため、エピタキシャル成長による薄膜形成が多用されている。 When manufacturing a power device, a high-frequency device, etc. using a SiC single crystal substrate, a SiC thin film is epitaxially grown on the substrate by a method called thermal CVD (thermochemical vapor deposition) or ion implantation is usually performed. In general, a dopant is directly implanted by a method, but in the latter case, annealing at a high temperature is required after implantation, and therefore thin film formation by epitaxial growth is frequently used.
近年、ＳｉＣデバイス技術の発展に伴い、ＳｉＣエピタキシャル基板に対しても、より高品質で大口径のものが求められてきている。エピタキシャル成長に用いられるＳｉＣ基板は、エピタキシャル成長の安定性、再現性の点からオフ角度の付いたものが使用されており、通常は８°である。このようなＳｉＣ基板は、表面が（０００１）面になっているＳｉＣインゴットから所望の角度をつけて切り出すことによって作成されており、オフ角度が大きいほど１個のインゴットから得られる基板の数は減少し、また、インゴットの大口径化と共に、長尺化は困難となる。したがって、大口径ＳｉＣ基板を効率よく製造するためには、オフ角度を小さくすることが必須となり、現在３インチ（７５ｍｍ）以上の口径を持つＳｉＣ基板に関しては、６°あるいはそれ以下のオフ角度を持った基板が主流であり、その基板を用いたエピタキシャル成長の研究が行われている。 In recent years, with the development of SiC device technology, SiC epitaxial substrates with higher quality and larger diameter have been demanded. As the SiC substrate used for epitaxial growth, a substrate with an off-angle is used from the viewpoint of stability and reproducibility of epitaxial growth, and is usually 8 °. Such a SiC substrate is produced by cutting out a desired angle from a SiC ingot whose surface is a (0001) plane, and the larger the off-angle, the greater the number of substrates obtained from one ingot. In addition, it becomes difficult to increase the length of the ingot as the diameter of the ingot increases. Therefore, in order to efficiently manufacture a large-diameter SiC substrate, it is essential to reduce the off-angle, and for an SiC substrate having a diameter of 3 inches (75 mm) or more, an off-angle of 6 ° or less is required. The substrate with the mainstream is the mainstream, and research on epitaxial growth using the substrate has been conducted.
しかし、オフ角度が小さくなると共に、基板上に存在するステップの数が減少するため、エピタキシャル成長時にステップ−フロー（ｓｔｅｐ−ｆｌｏｗ）成長が起こり難くなり、その結果、ステップ（ｓｔｅｐ）同士が集合する、所謂ステップ−バンチング（ｓｔｅｐ−ｂｕｎｃｈｉｎｇ）が発生する。 However, as the off-angle is reduced and the number of steps existing on the substrate is reduced, step-flow growth is less likely to occur during epitaxial growth, and as a result, steps are gathered together. So-called step-bunching occurs.
そこで、ステップ−バンチングの発生を抑える方法として、非特許文献１では、エピタキシャル成長を行う際に材料ガス（原料ガス）中に含まれる炭素と珪素の原子数比（Ｃ／Ｓｉ比）を下げる方法が報告されている。また、特許文献１では、成長初期のＣ／Ｓｉ比を０．５〜１．０に下げることで、らせん転位を起点とした渦巻成長の発生を抑え、周囲の大量のステップフローに覆われる確率を高めて、エピタキシャル欠陥を減らすことができるとしている。 Therefore, as a method of suppressing the occurrence of step-bunching, Non-Patent Document 1 discloses a method of reducing the atomic ratio (C / Si ratio) of carbon and silicon contained in a material gas (raw material gas) during epitaxial growth. It has been reported. Further, in Patent Document 1, by reducing the C / Si ratio at the initial stage of growth to 0.5 to 1.0, the occurrence of spiral growth starting from screw dislocation is suppressed, and the probability of being covered with a large amount of surrounding step flow It is said that the epitaxial defects can be reduced by increasing.
しかし、Ｃ／Ｓｉ比を下げると、残留窒素がエピタキシャル膜中に取り込まれ易くなり、これがドナーとして作用するため、膜の純度を上げることが困難となり、実用には適さない。 However, when the C / Si ratio is lowered, residual nitrogen is likely to be taken into the epitaxial film, and this acts as a donor, making it difficult to increase the purity of the film, which is not suitable for practical use.
また、特許文献２には、結晶欠陥密度が低く、結晶性のよいエピタキシャル薄膜を得るために、塩化水素ガスを添加した雰囲気中でエピタキシャル層を成長させることが開示されている。これは、添加した塩化水素によるエッチング作用（基板表面の清浄化）によって、エピタキシャル薄膜を単に結晶欠陥密度を低くして結晶性をよくするというものである。具体的には、オフ角度が８°のＳｉＣ基板に、３〜３０ｍＬ／ｍｉｎのＨＣｌ、０．３ｍＬ／ｍｉｎのＳｉＨ４のガスを含む条件（Ｃｌ／Ｓｉ比にすると、１０〜１００となる。）、即ち、成長中にＣｌ／Ｓｉ比が１００という塩化水素の割合を多くしてエッチング作用が促進する条件で、エピタキシャル成長させている。また、特許文献３では、熱ＣＶＤ法によるエピタキシャル成長の場合、部分的に立方晶（３Ｃ構造）のＳｉＣが形成されるという問題があるとし、前記問題を解決するために、珪素の水素化ガス、炭化水素ガス及びキャリヤガスと共に、ＨＣｌガスを同時に供給することが開示され、従来よりも小さい傾斜角度で傾いた（オフ角度が小さい）傾斜基板を用いて、ＳｉＣエピタキシャル層を成長できるとしている。Patent Document 2 discloses that an epitaxial layer is grown in an atmosphere to which hydrogen chloride gas is added in order to obtain an epitaxial thin film having a low crystal defect density and good crystallinity. This is to improve the crystallinity of the epitaxial thin film simply by reducing the crystal defect density by the etching action (cleaning of the substrate surface) of the added hydrogen chloride. Specifically, the condition is that the SiC substrate having an off angle of 8 ° contains 3 to 30 mL / min HCl and 0.3 mL / min SiH 4 gas (Cl / Si ratio is 10 to 100). That is, the epitaxial growth is performed under the condition that the etching action is promoted by increasing the proportion of hydrogen chloride having a Cl / Si ratio of 100 during the growth. Further, in Patent Document 3, in the case of epitaxial growth by a thermal CVD method, there is a problem that a cubic (3C structure) SiC is formed, and in order to solve the above problem, a hydrogenation gas of silicon, It is disclosed that HCl gas is supplied simultaneously with a hydrocarbon gas and a carrier gas, and it is said that a SiC epitaxial layer can be grown using a tilted substrate tilted at a tilt angle smaller than before (off angle is small).
なお、エピタキシャル成長させる前のＳｉＣ基板であるが、Ｃｌ２ガスやＨＣｌガスを用いてＳｉＣ基板の表面をエッチングして平滑にすることが特許文献４に開示されている。In addition, although it is a SiC substrate before epitaxially growing, patent document 4 discloses that the surface of the SiC substrate is etched and smoothed using Cl 2 gas or HCl gas.
また、特許文献５には、１２００℃程度の低い温度のＣＶＤ法による場合には珪素粒子が気相中に形成するという問題が発生し、前記問題を解決するために、ＨＣｌガスを添加することにより、反応を安定にし、珪素粒子が気相中に形成しないように作用することが開示されている。また、特許文献６では、低温ＣＶＤ法における原料ガスの反応を促進し、９００℃以下の低温域においてもＳｉＣ結晶膜を形成させるために、原料ガスにＨＣｌガスを混合している。また、低温ＣＶＤ法であるので、基板温度が１４００℃以下の温度で鏡面成長が可能であるとしている。さらに、特許文献７では、炭化珪素単結晶膜の表面を平坦にするために原料ガスにＨＣｌガスを添加しており、表面粗度が約５ｎｍの膜が作製されている。この表面粗度は、基板温度が１３５０℃としたＣＶＤ法で、シラン（ＳｉＨ４）０．２ＣＣＭの流量に対してＨＣｌガスが３ＣＣＭの流量（Ｃｌ／Ｓｉ比で１５である。）とすることにより得られている。Further, Patent Document 5 has a problem that silicon particles are formed in a gas phase when the CVD method is performed at a low temperature of about 1200 ° C. In order to solve the problem, HCl gas is added. Is disclosed to stabilize the reaction and prevent silicon particles from forming in the gas phase. In Patent Document 6, HCl gas is mixed with the source gas in order to promote the reaction of the source gas in the low temperature CVD method and form a SiC crystal film even in a low temperature region of 900 ° C. or lower. Further, since it is a low temperature CVD method, it is said that mirror growth is possible at a substrate temperature of 1400 ° C. or lower. Further, in Patent Document 7, HCl gas is added to the source gas in order to flatten the surface of the silicon carbide single crystal film, and a film having a surface roughness of about 5 nm is produced. This surface roughness is a CVD method in which the substrate temperature is 1350 ° C., and the flow rate of HCl gas is 3 CCM (Cl / Si ratio is 15) with respect to the flow rate of silane (SiH 4 ) 0.2 CCM. Is obtained.
したがって、今後デバイスへの応用が期待されるＳｉＣエピタキシャル成長基板であるが、基板の大口径化に伴い、オフ角度の小さい基板を使用するようになると、現状技術では、ステップ−バンチングの残ったエピタキシャル膜上にデバイスを作製することになる。本発明者らは、オフ角度の小さな基板上にデバイスを作製して詳細に検討した結果、次のようなことが明らかになった。このようなエピタキシャル膜の表面には多数の凸凹が生じており、デバイス電極下での電解集中を引き起こし易くなる。特に、ショットキーバリアダイオード、ＭＯＳトランジスタ等への応用を考えた場合、この電解集中はゲートリーク電流として顕著になり、デバイス特性を劣化させることになる。 Therefore, it is a SiC epitaxial growth substrate that is expected to be applied to devices in the future. However, with the increase in the substrate diameter, when a substrate with a small off angle is used, the state-of-the-art technology is an epitaxial film with step-bunching remaining. The device will be fabricated on top. The present inventors made a device on a substrate with a small off-angle and examined it in detail, and as a result, the following became clear. A number of irregularities are formed on the surface of such an epitaxial film, and it is easy to cause electrolytic concentration under the device electrode. In particular, when considering application to Schottky barrier diodes, MOS transistors, etc., this concentration of electrolysis becomes prominent as a gate leakage current, which degrades device characteristics.
上記のように、従来技術で得られるオフ角度の小さいＳｉＣ基板、即ち、６°以下のオフ角度のＳｉＣ基板では、ステップ−バンチングの発生を抑えた高品質エピタキシャル膜が得られず、デバイス特性やデバイス歩留が十分でないという問題があることが明らかになってきた。 As described above, a SiC substrate with a small off-angle obtained by the prior art, that is, a SiC substrate with an off-angle of 6 ° or less cannot obtain a high-quality epitaxial film in which the occurrence of step-bunching is suppressed. It has become clear that there is a problem of insufficient device yield.
また、ＳｉＣ基板にエピタキシャル膜を成長させる方法に関し、上記の特許文献に記載されているような方法が知られている。 In addition, regarding a method for growing an epitaxial film on a SiC substrate, a method as described in the above patent document is known.
しかしながら、特許文献２及び３は、６°以下のオフ角度のＳｉＣ基板にエピタキシャル成長する場合に、ステップ−バンチングの発生を抑えることを開示するものではない。実際に、本発明者らが、これらの文献に開示される条件を検討したところ、６°以下のオフ角度のＳｉＣ基板では、ステップ−バンチングの発生を抑えた高品質エピタキシャル膜が得られず、デバイス特性やデバイス歩留が十分ではない。また、同様に、特許文献５〜７と同様の条件を検討したが、基板温度が低く、６°以下のオフ角度のＳｉＣ基板では、ステップ−バンチングの発生を抑えた高品質エピタキシャル膜、即ち、サブｎｍレベル以下の表面粗度となるような平坦な表面を有するエピタキシャル膜が得られず、デバイス特性やデバイス歩留が十分ではない。 However, Patent Documents 2 and 3 do not disclose that generation of step-bunching is suppressed when epitaxially growing on a SiC substrate having an off angle of 6 ° or less. Actually, the present inventors examined the conditions disclosed in these documents, and with a SiC substrate having an off angle of 6 ° or less, a high-quality epitaxial film with suppressed generation of step-bunching cannot be obtained. Device characteristics and device yield are not sufficient. Similarly, the same conditions as in Patent Documents 5 to 7 were examined. However, in a SiC substrate having a low substrate temperature and an off angle of 6 ° or less, a high-quality epitaxial film in which generation of step-bunching is suppressed, that is, An epitaxial film having a flat surface with a surface roughness below the sub-nm level cannot be obtained, and device characteristics and device yield are not sufficient.
本発明は、上記オフ角度が６°乃至それ以下の基板を用いたエピタキシャル成長において、ステップ−バンチングの発生を抑えた高品質エピタキシャル膜を有するエピタキシャルあ単結晶基板及びその製造方法を提供することを目的とする。 An object of the present invention is to provide an epitaxial single crystal substrate having a high-quality epitaxial film in which generation of step-bunching is suppressed in epitaxial growth using a substrate having an off angle of 6 ° or less and a method for manufacturing the same. And
本発明は、エピタキシャル成長時に流す材料ガス（原料ガス）中に、特定の条件で塩化水素ガスを添加することで上記課題を解決できることを見出し、完成したものである。更に、前記方法により、ステップ−バンチングの発生が抑えられた結果、オフ角度が６°以下のＳｉＣ基板を用いたエピタキシャルＳｉＣ単結晶基板を作製できるようになり、該エピタキシャルＳｉＣ単結晶基板を用いてデバイス特性やデバイス歩留を詳細に検討した。オフ角度が６°以下のＳｉＣ基板を用いたエピタキシャルＳｉＣ単結晶基板で、炭化珪素単結晶薄膜表面が、表面粗さ（Ｒａ値）が０．５ｎｍ以下のものが得られていなかったので、該表面粗さレベルにおけるデバイス特性やデバイス歩留は知られていなかったが、本発明者らは、上記方法で作製したエピタキシャルＳｉＣ単結晶基板を用いて検討した結果、炭化珪素単結晶薄膜表面が、表面粗さ（Ｒａ値）が０．５ｎｍ以下であると、デバイス特性やデバイス歩留が顕著に向上することを見出した。 The present invention has been completed by finding that the above-mentioned problems can be solved by adding hydrogen chloride gas under specific conditions to a material gas (raw material gas) that flows during epitaxial growth. Furthermore, as a result of suppressing the occurrence of step-bunching by the above method, an epitaxial SiC single crystal substrate using an SiC substrate having an off angle of 6 ° or less can be produced. Using the epitaxial SiC single crystal substrate, The device characteristics and device yield were examined in detail. Since an epitaxial SiC single crystal substrate using an SiC substrate having an off angle of 6 ° or less, a silicon carbide single crystal thin film surface having a surface roughness (Ra value) of 0.5 nm or less was not obtained. Although the device characteristics and device yield at the surface roughness level were not known, the present inventors examined using the epitaxial SiC single crystal substrate produced by the above method, the silicon carbide single crystal thin film surface, It has been found that device characteristics and device yield are remarkably improved when the surface roughness (Ra value) is 0.5 nm or less.
即ち、本発明の要旨は次のとおりである。
（１）オフ角度が６°以下である炭化珪素単結晶基板上に炭化珪素単結晶薄膜を形成したエピタキシャル炭化珪素単結晶基板であって、前記炭化珪素単結晶薄膜表面の表面粗さ（Ｒａ値）が０．５ｎｍ以下であることを特徴とするエピタキシャル炭化珪素単結晶基板。
（２）オフ角度が６°以下である炭化珪素単結晶基板上に、熱化学蒸着法で炭化珪素単結晶薄膜をエピタキシャル成長させる際に、炭素と珪素を含む原料ガスを流すと同時に塩化水素ガスを流し、原料ガス中の珪素原子数に対する塩化水素ガス中の塩素原子数の比（Ｃｌ／Ｓｉ比）が１．０より大きく２０．０より小さくすることを特徴とするエピタキシャル炭化珪素単結晶基板の製造方法。
（３）前記炭化珪素単結晶薄膜をエピタキシャル成長する際の、原料ガス中に含まれる、炭素と珪素の原子数比（Ｃ／Ｓｉ比）が１．５以下であることを特徴とする上記（２）に記載のエピタキシャル炭化珪素単結晶基板の製造方法。That is, the gist of the present invention is as follows.
(1) An epitaxial silicon carbide single crystal substrate in which a silicon carbide single crystal thin film is formed on a silicon carbide single crystal substrate having an off angle of 6 ° or less, and the surface roughness (Ra value) of the silicon carbide single crystal thin film surface. ) Is 0.5 nm or less. Epitaxial silicon carbide single crystal substrate characterized by the above-mentioned.
(2) When a silicon carbide single crystal thin film is epitaxially grown by a thermal chemical vapor deposition method on a silicon carbide single crystal substrate having an off angle of 6 ° or less, a source gas containing carbon and silicon is flowed simultaneously with hydrogen chloride gas. A ratio of the number of chlorine atoms in the hydrogen chloride gas to the number of silicon atoms in the source gas (Cl / Si ratio) is greater than 1.0 and less than 20.0; Production method.
(3) The atomic ratio (C / Si ratio) of carbon and silicon contained in the source gas when epitaxially growing the silicon carbide single crystal thin film is 1.5 or less (2) The method for producing an epitaxial silicon carbide single crystal substrate as described in 1).
本発明によれば、基板のオフ角度が６°乃至それ以下であっても、ステップ−バンチングの発生を抑え、表面粗さのＲａ値の小さい高品質なエピタキシャル膜を有するＳｉＣ単結晶基板を提供することが可能である。 According to the present invention, there is provided an SiC single crystal substrate having a high-quality epitaxial film that suppresses generation of step-bunching and has a small surface roughness Ra value even when the off-angle of the substrate is 6 ° or less. Is possible.
また、本発明の製造方法は、熱ＣＶＤ法であるため、装置構成が容易で制御性にも優れ、均一性、再現性の高いエピタキシャル膜が得られる。 In addition, since the manufacturing method of the present invention is a thermal CVD method, an epitaxial film with an easy apparatus configuration, excellent controllability, and high uniformity and reproducibility can be obtained.
さらに、本発明のエピタキシャルＳｉＣ単結晶基板を用いたデバイスは、表面粗さＲａ値の小さい、平坦性に優れた高品質エピタキシャル膜上に形成されるため、その特性及び歩留りが向上する。 Furthermore, since the device using the epitaxial SiC single crystal substrate of the present invention is formed on a high quality epitaxial film having a small surface roughness Ra value and excellent flatness, the characteristics and yield are improved.
本発明の具体的な内容について述べる。
まず、ＳｉＣ単結晶基板上へのエピタキシャル成長について述べる。
本発明で好適にエピタキシャル成長に用いる装置は、横型の熱ＣＶＤ装置である。熱ＣＶＤ法は、装置構成が簡単であり、ガスのｏｎ／ｏｆｆで成長を制御できるため、エピタキシャル膜の制御性、再現性に優れた成長方法である。The specific contents of the present invention will be described.
First, epitaxial growth on a SiC single crystal substrate will be described.
The apparatus preferably used for epitaxial growth in the present invention is a horizontal thermal CVD apparatus. The thermal CVD method has a simple apparatus configuration and can control growth by turning gas on / off. Therefore, the thermal CVD method is excellent in controllability and reproducibility of the epitaxial film.
図６に、従来のエピタキシャル膜成長を行う際の典型的な成長シーケンスを、ガスの導入タイミングと併せて示す。まず、成長炉に基板をセットし、成長炉内を真空排気した後、水素ガスを導入して圧力を１×１０４〜３×１０４Ｐａに調整する。その後、圧力を一定に保ちながら成長炉の温度を上げ、１４００℃程度で１０〜３０分間、水素中あるいは塩化水素を導入して塩化水素中での基板のエッチングを行う。これは、研磨等に伴う基板表面の変質層を取り除き、清浄な表面を出すためのものである。前記基板のエッチング工程は、炭化珪素単結晶膜の成長前に基板表面を清浄にするために好ましいが、該工程が無くても本発明の効果が得られる。例えば、既に、清浄な表面を有する基板であれば、基板のエッチング工程はなくてもよい。その後、温度を成長温度である１５００〜１６００℃又は１５００〜１６５０℃に上げ、材料ガス（原料ガス）であるＳｉＨ４とＣ２Ｈ４を導入して成長を開始する（即ち、１５００℃以上で成長させるという熱ＣＶＤ法である。）。ＳｉＨ４流量は毎分４０〜５０ｃｍ３、Ｃ２Ｈ４流量は毎分２０〜４０ｃｍ３又は３０〜４０ｃｍ３であり、成長速度は毎時６〜７μｍである。この成長速度は、通常利用されるエピタキシャル層の膜厚が１０μｍ程度であるため、生産性を考慮して決定されたものである。一定時間成長し、所望の膜厚が得られた時点でＳｉＨ４とＣ２Ｈ４の導入を止め、水素ガスのみ流した状態で温度を下げる。温度が常温まで下がった後、水素ガスの導入を止め、成長室内を真空排気し、不活性ガスを成長室に導入して、成長室を大気圧に戻してから、基板を取り出す。FIG. 6 shows a typical growth sequence in performing conventional epitaxial film growth together with gas introduction timing. First, a substrate is set in a growth furnace, the inside of the growth furnace is evacuated, and then hydrogen gas is introduced to adjust the pressure to 1 × 10 4 to 3 × 10 4 Pa. Thereafter, the temperature of the growth furnace is raised while keeping the pressure constant, and the substrate is etched in hydrogen chloride by introducing hydrogen or hydrogen chloride at about 1400 ° C. for 10 to 30 minutes. This is for removing the altered layer on the surface of the substrate due to polishing or the like, and providing a clean surface. The substrate etching step is preferable for cleaning the substrate surface before the growth of the silicon carbide single crystal film, but the effect of the present invention can be obtained without this step. For example, if the substrate already has a clean surface, the substrate etching step may be omitted. Thereafter, the temperature is raised to a growth temperature of 1500 to 1600 ° C. or 1500 to 1650 ° C., and SiH 4 and C 2 H 4 which are material gases (raw material gases) are introduced to start growth (ie, at 1500 ° C. or higher). It is a thermal CVD method of growing.) SiH 4 flow rate per minute 40~50cm 3, C 2 H 4 flow rate per minute 20 to 40 cm 3 or 30~40cm 3, the growth rate is per hour 6～7Myuemu. This growth rate is determined in consideration of productivity because the film thickness of the normally used epitaxial layer is about 10 μm. When the film is grown for a certain time and a desired film thickness is obtained, the introduction of SiH 4 and C 2 H 4 is stopped, and the temperature is lowered while only hydrogen gas is allowed to flow. After the temperature has dropped to room temperature, the introduction of hydrogen gas is stopped, the growth chamber is evacuated, an inert gas is introduced into the growth chamber, the growth chamber is returned to atmospheric pressure, and the substrate is taken out.
次に、本発明の内容を図６の成長シーケンスで説明する。ＳｉＣ単結晶基板をセットし、水素あるいは塩化水素中でのエッチングまでは、図６と同様である。その後、１５００〜１６００℃又は１５００〜１６５０℃の成長温度に上げ、材料ガスであるＳｉＨ４とＣ２Ｈ４を流して成長を開始するが、この時同時にＨＣｌガスも導入する。ＳｉＨ４流量は毎分４０〜５０ｃｍ３、Ｃ２Ｈ４流量は毎分２０〜４０ｃｍ３又は３０〜４０ｃｍ３であり、ＨＣｌの流量は、ガス中のＳｉとＣｌの原子数の比（Ｃｌ／Ｓｉ比）が１．０〜２０．０になるようにして、毎分４０〜１０００ｃｍ３程度が好ましい。成長速度はＨＣｌガスを流さない場合とほぼ同じであり、所望の膜厚が得られた時点でＳｉＨ４とＣ２Ｈ４及びＨＣｌの導入を止める。その後の手順は、ＨＣｌガスを流さない場合と同様である。このように、原料ガスとＨＣｌガスを同時に流すことにより、６°乃至それ以下という小さいオフ角を持った基板上であっても、表面のステップ−バンチングの発生が抑えられた良好なエピタキシャル膜が得られるようになる。Next, the contents of the present invention will be described with reference to the growth sequence of FIG. The process up to setting the SiC single crystal substrate and etching in hydrogen or hydrogen chloride is the same as in FIG. Thereafter, the growth temperature is increased to 1500 to 1600 ° C. or 1500 to 1650 ° C., and SiH 4 and C 2 H 4 which are material gases are supplied to start the growth. At this time, HCl gas is also introduced. SiH 4 flow rate per minute 40~50cm 3, C 2 H 4 flow rate per minute 20 to 40 cm 3 or 30～40Cm 3, the flow rate of the HCl, the ratio of the number of atoms of Si and Cl in the gas (Cl / The Si ratio is preferably about 1.0 to 20.0, and is preferably about 40 to 1000 cm 3 per minute. The growth rate is almost the same as when HCl gas is not flown, and the introduction of SiH 4 , C 2 H 4 and HCl is stopped when a desired film thickness is obtained. The subsequent procedure is the same as that when no HCl gas is flowed. In this way, by supplying the source gas and the HCl gas simultaneously, a good epitaxial film in which the occurrence of step-bunching on the surface is suppressed even on a substrate having a small off angle of 6 ° or less can be obtained. It will be obtained.
これは以下のように考えられる。成長表面でのステップ−フローを阻害する一因として、ＳｉＨ４の分解により発生したＳｉ原子が気相中で結合し、それが核となってＳｉドロップレット（ｄｒｏｐｌｅｔ）を形成して、基板上に付着することが考えられる。あるいは、過剰のＳｉ原子が成長表面で凝集する可能性も否定できない。特に、基板のオフ角度が小さくなり、テラスの幅が大きくなるに従い、上記の現象は顕著になってくると思われる。それが、ＨＣｌガスを導入することにより、ＨＣｌが分解して発生したＣｌが、気相中でＳｉ−Ｃｌの形を取ることにより、Ｓｉ同士の結合を抑え、あるいは成長表面での過剰ＳｉをＳｉＨｘＣｌｙの形で再蒸発させる等の効果が得られ、その結果、ステップ−フロー成長が、小さいオフ角を持った基板上でも持続したためと考えられる。This is considered as follows. As one factor that hinders the step-flow on the growth surface, Si atoms generated by the decomposition of SiH 4 are bonded in the gas phase, which forms nuclei to form Si droplets on the substrate. It is thought that it adheres to. Or the possibility that excessive Si atoms aggregate on the growth surface cannot be denied. In particular, the above phenomenon seems to become more prominent as the off-angle of the substrate decreases and the terrace width increases. By introducing HCl gas, Cl generated by decomposition of HCl takes the form of Si-Cl in the gas phase, thereby suppressing the bonding between Si or excess Si on the growth surface. It is considered that an effect such as re-evaporation in the form of SiH x Cl y was obtained, and as a result, step-flow growth was sustained even on a substrate having a small off angle.
一方、オフ角度の小さなＳｉＣ基板上にエピタキシャル成長を行う際、ＨＣｌを使用するものとして、前述したように、特許文献２及び３に提案される方法がある。しかし、特許文献２の方法の場合は、基板表面の清浄化によるエピタキシャル膜の品質向上（エッチピット密度の減少）を目的としている。その実施例においては、８°オフ角度の基板を用いた場合であり、６°乃至それ以下のオフ角度を持った基板上にエピタキシャル成長する際のステップ−バンチング発生防止に関するものではない。また、特許文献３の方法の場合は、６°以下のオフ角を持った基板上エピタキシャル成長の場合も含まれているが、ＨＣｌを添加する効果として、ＨＣｌのエッチングにより基板表面に強制的にステップを形成することを挙げており、ステップが増加することで、表面での３Ｃ−ＳｉＣの発生が防げるとしている。したがって、ＨＣｌが分解して発生したＣｌとＳｉとの反応を利用して、表面粗さＲａを０．５ｎｍ以下とする本発明とは基本的に異なる。 On the other hand, as described above, there is a method proposed in Patent Documents 2 and 3 that uses HCl when performing epitaxial growth on a SiC substrate having a small off-angle. However, the method of Patent Document 2 aims at improving the quality of the epitaxial film (decreasing the etch pit density) by cleaning the substrate surface. In this embodiment, a substrate having an off angle of 8 ° is used, and it does not relate to prevention of step-bunching when epitaxially growing on a substrate having an off angle of 6 ° or less. In addition, the method of Patent Document 3 includes the case of epitaxial growth on a substrate having an off angle of 6 ° or less. However, as an effect of adding HCl, the surface of the substrate is forcibly stepped by etching of HCl. The formation of 3C-SiC on the surface can be prevented by increasing the number of steps. Therefore, the present invention is basically different from the present invention in which the surface roughness Ra is 0.5 nm or less by utilizing the reaction between Cl and Si generated by the decomposition of HCl.
即ち、本発明では、エピタキシャル成長中に、その原料ガスとともにＨＣｌガスを導入するものであるが、前述のように、本発明では、ＨＣｌのエッチング作用を利用するのではなく、気相中でＳｉ−Ｃｌの形をとり、Ｓｉ同士の結合を抑制するという作用を利用するものであるので、エピタキシャル膜の成長速度はＨＣｌを導入にない場合とほぼ同様に十分大きい。具体的には、エッチング作用が殆ど起こらないような、ＨＣｌ導入量の少ない条件（Ｃｌ／Ｓｉ比で１．０〜２０．０の範囲）である。特許文献２では、前述のように、オフ角度が８°のＳｉＣ基板ではあるが、Ｃｌ／Ｓｉ比にすると１０〜１００となる範囲で成長中にＨＣｌを導入するとしている。しかしながら、成長中にＣｌ／Ｓｉ比が２０を超えるというようなＨＣｌを多量に導入する条件を含むので、本発明の上記効果が得られない。本発明の効果を得るためには、成長中に導入するＨＣｌの量はＣｌ／Ｓｉ比で２０．０を超えないようにすることが重要である。 That is, in the present invention, HCl gas is introduced together with the source gas during epitaxial growth. However, as described above, in the present invention, the etching action of HCl is not used, but Si— Since it takes the form of Cl and uses the action of suppressing the bonding between Si, the growth rate of the epitaxial film is sufficiently large as in the case where HCl is not introduced. Specifically, the conditions are such that the amount of HCl introduced is small (Cl / Si ratio is in the range of 1.0 to 20.0) so that the etching action hardly occurs. In Patent Document 2, as described above, although the SiC substrate has an off angle of 8 °, HCl is introduced during growth in a range of 10 to 100 when the Cl / Si ratio is set. However, the above-described effect of the present invention cannot be obtained because it includes conditions for introducing a large amount of HCl such that the Cl / Si ratio exceeds 20 during growth. In order to obtain the effect of the present invention, it is important that the amount of HCl introduced during growth does not exceed 20.0 in terms of Cl / Si ratio.
本発明により、６°乃至それ以下という小さいオフ角度（即ち、０°〜６°のオフ角度である。）を持った基板上であっても、表面のステップ−バンチングの発生が抑えられた良好なエピタキシャル膜が得られるようになったが、成長するエピタキシャル層の厚さについては、通常形成されるデバイスの耐圧、エピタキシャル膜の生産性等を考慮した場合、５μｍ以上５０μｍ以下が好ましい。また、オフ角度が０°超でオフ角度を有する基板がエピタキシャル膜の成長し易さの点から好ましい。さらに、基板のオフ角度については、１°以下であると、表面に存在するステップの数が少なくなり、本発明の効果が現れ難くなるため、１°より大きく６°以下が好ましい。また、成長時のガス中に含まれるＣｌ／Ｓｉ比は、１．０より小さいとＨＣｌガスを添加した効果が現れず、２０．０より大きいとＨＣｌガスによるエッチングが行われて来るため、１．０から２０．０の間が望ましいが、より好適には４．０〜１０．０の間である。更に好ましいＣｌ／Ｓｉ比は、４．０以上１０．０未満である。 According to the present invention, even on a substrate having a small off angle of 6 ° or less (that is, an off angle of 0 ° to 6 °), the occurrence of surface step-bunching is suppressed. An epitaxial film can be obtained, but the thickness of the grown epitaxial layer is preferably 5 μm or more and 50 μm or less in consideration of the breakdown voltage of a normally formed device, the productivity of the epitaxial film, and the like. Further, a substrate having an off angle exceeding 0 ° and an off angle is preferable from the viewpoint of easy growth of the epitaxial film. Furthermore, if the off-angle of the substrate is 1 ° or less, the number of steps existing on the surface is reduced, and the effects of the present invention are hardly exhibited. Further, if the Cl / Si ratio contained in the gas during growth is smaller than 1.0, the effect of adding HCl gas does not appear, and if it is larger than 20.0, etching with HCl gas is performed. It is preferably between 0.0 and 20.0, but more preferably between 4.0 and 10.0. A more preferable Cl / Si ratio is 4.0 or more and less than 10.0.
さらに、材料ガスにおけるＣ／Ｓｉ比は、ステップ−フロー成長を促進するため１．５以下が望ましいが、１．０より小さいと、所謂サイト−コンペティション（ｓｉｔｅ−ｃｏｍｐｅｔｉｔｉｏｎ）効果で、残留窒素の取り込みが大きくなり、エピタキシャル膜の純度が下がるため、より好適には１．０〜１．５の間である。 Further, the C / Si ratio in the material gas is preferably 1.5 or less in order to promote step-flow growth, but if it is less than 1.0, the so-called site-competition effect takes in the residual nitrogen. Is increased, and the purity of the epitaxial film is lowered. Therefore, it is more preferably between 1.0 and 1.5.
また、本発明では、オフ角度が６°以下であるＳｉＣ基板は、直径２インチ以上（直径５０ｍｍ以上）のサイズである方が、本発明の効果がより顕著に得られる。ＳｉＣ基板が小さい場合（例えば、直径２インチ（直径５０ｍｍ）未満では）、熱ＣＶＤ法における基板の加熱は全基板表面に均一に行うことが容易であり、その結果、ステップ−バンチングの発生が起きにくい。 In the present invention, the effect of the present invention can be obtained more significantly when the SiC substrate having an off angle of 6 ° or less is 2 inches or more in diameter (50 mm or more in diameter). When the SiC substrate is small (for example, less than 2 inches in diameter (diameter 50 mm)), it is easy to heat the substrate in the thermal CVD method uniformly over the entire substrate surface, and as a result, step-bunching occurs. Hateful.
よって、本発明の条件でＨＣｌを導入しても、ステップ−バンチングの発生の抑制効果を発揮できない場合がある。但し、小さなＳｉＣ基板でも加熱法が不均一あると、ステップ−バンチングの発生が起きやすくなるので、本発明の効果が顕著に得られる。一方、ＳｉＣ基板が大きくなり、直径２インチ（直径５０ｍｍ）以上になると、基板表面全体を均一に加熱すること（均一な温度に保つこと）が難しくなるので、結晶成長の速度が場所によって異なるようになり、その結果、ステップ−バンチングが発生しやすいようになる。したがって、このようなステップ−バンチングが発生しやすいような大きなＳｉＣ基板では、本発明の条件でＨＣｌを導入することでステップ−バンチングの発生を抑制するという効果を十分発揮できる。 Therefore, even if HCl is introduced under the conditions of the present invention, the effect of suppressing the occurrence of step-bunching may not be exhibited. However, if the heating method is not uniform even with a small SiC substrate, step-bunching is likely to occur, so that the effects of the present invention are remarkably obtained. On the other hand, if the SiC substrate becomes large and becomes 2 inches in diameter (diameter 50 mm) or more, it becomes difficult to uniformly heat the entire substrate surface (maintain a uniform temperature). As a result, step-bunching is likely to occur. Therefore, in a large SiC substrate in which such step-bunching is likely to occur, the effect of suppressing the occurrence of step-bunching can be sufficiently exhibited by introducing HCl under the conditions of the present invention.
そして、本発明によれば、ＳｉＣ単結晶基板にエピタキシャル膜を成長する際に所定の流量のＨＣｌガスを存在させることにより、表面粗さ（Ｒａ値）が０．５ｎｍ以下といった高品質のＳｉＣ単結晶薄膜を得ることができる。尚、表面粗さＲａはＪＩＳ Ｂ０６０１：２００１に準拠する算術平均粗さである。本発明の製造方法においてより最適な条件とすれば、表面粗（Ｒａ値）が０．４ｎｍ以下の更に高品質のＳｉＣ単結晶薄膜を容易に得ることができる。 According to the present invention, when an epitaxial film is grown on an SiC single crystal substrate, a high-quality SiC single layer having a surface roughness (Ra value) of 0.5 nm or less is obtained by allowing HCl gas at a predetermined flow rate to exist. A crystalline thin film can be obtained. The surface roughness Ra is an arithmetic average roughness based on JIS B0601: 2001. If the conditions are more optimal in the production method of the present invention, a higher quality SiC single crystal thin film having a surface roughness (Ra value) of 0.4 nm or less can be easily obtained.
更に、本発明によって、表面粗さ（Ｒａ値）が０．５ｎｍ以下を含む表面粗さの異なる種々のエピタキシャル膜を有するＳｉＣ単結晶基板を作製し、それぞれのデバイス特性やデバイス歩留を調べた。その結果、下記の実施例にも示すように、ＳｉＣ単結晶薄膜表面が、表面粗さ（Ｒａ値）が０．５ｎｍ以下、好ましくは０．４ｎｍ以下であると、デバイス特性やデバイス歩留が顕著に向上することを見出した。 Furthermore, according to the present invention, SiC single crystal substrates having various epitaxial films with different surface roughnesses including a surface roughness (Ra value) of 0.5 nm or less were fabricated, and the device characteristics and device yields were examined. . As a result, as shown in the following examples, when the surface of the SiC single crystal thin film has a surface roughness (Ra value) of 0.5 nm or less, preferably 0.4 nm or less, device characteristics and device yield are reduced. It has been found that it is significantly improved.
このようにして成長されたエピタキシャル基板上に好適に形成されるデバイスは、ショットキーバリアダイオード、ＰＩＮダイオード、ＭＯＳダイオード、ＭＯＳトランジスタ等、特に電力制御用に用いられるデバイスである。 Devices suitably formed on the epitaxial substrate thus grown are Schottky barrier diodes, PIN diodes, MOS diodes, MOS transistors, and the like, particularly devices used for power control.
（実施例１）
２インチ（５０ｍｍ）ウェーハ用ＳｉＣ単結晶インゴットから、約４００μｍの厚さでスライスし、粗削りとダイヤモンド砥粒による通常研磨を実施した、４Ｈ型のポリタイプを有するＳｉＣ単結晶基板のＳｉ面に、エピタキシャル成長を実施した。基板のオフ角は４°である。成長の手順としては、成長炉に基板をセットし、成長炉内を真空排気した後、水素ガスを毎分１５０Ｌ導入しながら圧力を１．０×１０４Ｐａに調整した。その後、圧力を一定に保ちながら成長炉の温度を上げ、１５５０℃に到達した後、塩化水素を毎分１０００ｃｍ３流し、２０分間基板のエッチングを行った。エッチング後、温度を１６００℃まで上げ、ＳｉＨ４流量を毎分４０ｃｍ３、Ｃ２Ｈ４流量を毎分２２ｃｍ３（Ｃ／Ｓｉ＝１．１）、ＨＣｌ流量を毎分２００ｃｍ３（Ｃｌ／Ｓｉ＝５．０）にしてエピタキシャル層を１０μｍ成長した。この時の成長速度は毎時７μｍ程度であった。Example 1
From a SiC single crystal ingot for a 2-inch (50 mm) wafer, sliced at a thickness of about 400 μm, and subjected to rough grinding and normal polishing with diamond abrasive grains, on the Si surface of a SiC single crystal substrate having a 4H type polytype, Epitaxial growth was performed. The off angle of the substrate is 4 °. As a growth procedure, a substrate was set in a growth furnace, the inside of the growth furnace was evacuated, and then the pressure was adjusted to 1.0 × 10 4 Pa while introducing 150 L of hydrogen gas per minute. Thereafter, the temperature of the growth furnace was raised while keeping the pressure constant, and after reaching 1550 ° C., 1000 cm 3 of hydrogen chloride was flowed per minute and the substrate was etched for 20 minutes. After etching, the temperature was raised to 1600 ° C., the SiH 4 flow rate was 40 cm 3 / min, the C 2 H 4 flow rate was 22 cm 3 / min (C / Si = 1.1), and the HCl flow rate was 200 cm 3 / min (Cl / Si = 5.0), the epitaxial layer was grown to 10 μm. The growth rate at this time was about 7 μm per hour.
このようにしてエピタキシャル成長を行った膜の表面の光学顕微鏡写真を図３に、また表面ＡＦＭ像を図３に示す。図２から、表面は鏡面になっており、ステップ−バンチングが生じていないことが分かる。また、図３から、表面粗さのＲａ値は０．２１ｎｍであることが分かり、これは８°オフ基板上のエピタキシャル成長膜の値とほぼ同等であった。このようなエピタキシャル膜を用いてショットキーバリアダイオード（直径２００μｍ）を形成した際の、ダイオードの順方向特性を図４に示す。図４から、電流の立ち上がり時の直線性は良好であり、ダイオードの性能を示すｎ値が１．０１と、ほぼ理想的な特性が得られていることが分かった。また、前記と同様に、同基板上にショットキーバリアオードを更に１００個作製して同じ評価を行ったところ、全て不良なく同様の特性を示した。 An optical micrograph of the surface of the film epitaxially grown in this way is shown in FIG. 3, and a surface AFM image is shown in FIG. It can be seen from FIG. 2 that the surface is a mirror and no step-bunching has occurred. Further, FIG. 3 shows that the Ra value of the surface roughness is 0.21 nm, which is almost equal to the value of the epitaxially grown film on the 8 ° off substrate. FIG. 4 shows the forward characteristics of a diode when a Schottky barrier diode (diameter 200 μm) is formed using such an epitaxial film. From FIG. 4, it was found that the linearity at the time of rising of the current was good, and the n value indicating the performance of the diode was 1.01, and almost ideal characteristics were obtained. Similarly to the above, when 100 Schottky barrier anodes were further produced on the same substrate and subjected to the same evaluation, all showed the same characteristics without any defects.
（実施例２）
実施例１と同様にスライス、粗削り、通常研磨を行った、４Ｈ型のポリタイプを有する２インチ（５０ｍｍ）のＳｉＣ単結晶基板のＳｉ面に、エピタキシャル成長を実施した。基板のオフ角は４°である。成長手順、温度等は、実施例１と同様であるが、ガス流量は、ＳｉＨ４流量を毎分４０ｃｍ３、Ｃ２Ｈ４流量を毎分２２ｃｍ３（Ｃ／Ｓｉ＝１．１）、ＨＣｌ流量を毎分４００ｃｍ３（Ｃｌ／Ｓｉ＝１０．０）にして、エピタキシャル層を１０μｍ成長した。成長後のエピタキシャル膜の光学顕微鏡写真を図５に示す。図５から、この条件の場合もステップ−バンチングの生じていない良好な膜であることが分かる。また、ＡＦＭ評価から、表面粗さのＲａ値は０．１６ｎｍであった。成長後、実施例１と同様にショットキーバリアダイオードを形成し、成長中にＨＣｌを添加しない、従来の方法による４°オフ基板上のエピタキシャル膜上に形成したショットキーバリアダイオードと共に逆方向の耐圧を評価した。それぞれのダイオードを１００個評価した結果は、本発明によるエピタキシャル膜上のダイオードの耐圧（中央値）が３４０Ｖ、従来方法によるエピタキシャル膜（表面粗さのＲａ値：２．５ｎｍ）上のダイオードの耐圧（中央値）が３２０Ｖであり、本発明によるエピタキシャル膜上のダイオードの方が優れた特性を示していた。本発明によるエピタキシャル膜上に作製した１００個のダイオードは、全て不良のないものであった。従来方法によるエピタキシャル膜上に作製した１００個のダイオードの内、５個の不良が発生した。(Example 2)
Epitaxial growth was performed on the Si surface of a 2 inch (50 mm) SiC single crystal substrate having a 4H-type polytype, which was sliced, roughly ground, and normally polished in the same manner as in Example 1. The off angle of the substrate is 4 °. The growth procedure, temperature, etc. are the same as in Example 1, but the gas flow rate is 40 cm 3 per minute for the SiH 4 flow rate, 22 cm 3 per minute for the C 2 H 4 flow rate (C / Si = 1.1), HCl The flow rate was 400 cm 3 / min (Cl / Si = 10.0), and the epitaxial layer was grown to 10 μm. An optical micrograph of the grown epitaxial film is shown in FIG. From FIG. 5, it can be seen that even under this condition, the film is a good film with no step-bunching. From the AFM evaluation, the Ra value of the surface roughness was 0.16 nm. After the growth, a Schottky barrier diode is formed in the same manner as in Example 1, and HCl is not added during the growth, and withstand voltage in the reverse direction together with the Schottky barrier diode formed on the epitaxial film on the 4 ° off substrate by the conventional method. Evaluated. As a result of evaluating 100 diodes, the breakdown voltage (median value) of the diode on the epitaxial film according to the present invention is 340 V, and the breakdown voltage of the diode on the epitaxial film (Ra value of surface roughness: 2.5 nm) according to the conventional method. The (median) was 320 V, and the diode on the epitaxial film according to the present invention exhibited superior characteristics. All 100 diodes fabricated on the epitaxial film according to the present invention were free from defects. Of the 100 diodes fabricated on the epitaxial film by the conventional method, 5 defects occurred.
（実施例３）
実施例１と同様にスライス、粗削り、通常研磨を行った、４Ｈ型のポリタイプを有する２インチ（５０ｍｍ）のＳｉＣ単結晶基板のＳｉ面に、エピタキシャル成長を実施した。基板のオフ角は４°である。成長手順、温度等は、実施例１と同様であるが、ガス流量は、ＳｉＨ４流量を毎分４０ｃｍ３、Ｃ２Ｈ４流量を毎分２８ｃｍ３（Ｃ／Ｓｉ＝１．４）、ＨＣｌ流量を毎分２００ｃｍ３（Ｃｌ／Ｓｉ＝５．０）にして、エピタキシャル層を１０μｍ成長した。成長後のエピタキシャル膜はステップ−バンチングの生じていない良好な膜であり、表面粗さのＲａ値は０．２３ｎｍであった。実施例１と同様にショットキーバリアダイオードを形成し、ｎ値を求めると１．０１であり、この場合もほぼ理想的な特性が得られていることが分かった。また、前記と同様に、同基板上にショットキーバリアオードを更に１００個作製して同じ評価を行ったところ、全て不良なく同様の特性を示した。(Example 3)
Epitaxial growth was performed on the Si surface of a 2 inch (50 mm) SiC single crystal substrate having a 4H-type polytype, which was sliced, roughly ground, and normally polished in the same manner as in Example 1. The off angle of the substrate is 4 °. The growth procedure, temperature, and the like are the same as in Example 1, but the gas flow rate is 40 cm 3 per minute for the SiH 4 flow rate, 28 cm 3 per minute for the C 2 H 4 flow rate (C / Si = 1.4), HCl The epitaxial layer was grown to 10 μm at a flow rate of 200 cm 3 / min (Cl / Si = 5.0). The grown epitaxial film was a good film with no step-bunching, and the Ra value of the surface roughness was 0.23 nm. When a Schottky barrier diode was formed in the same manner as in Example 1 and the n value was obtained, it was 1.01, and it was found that almost ideal characteristics were also obtained in this case. Similarly to the above, when 100 Schottky barrier anodes were further produced on the same substrate and subjected to the same evaluation, all showed the same characteristics without any defects.
（実施例４）
実施例１と同様にスライス、粗削り、通常研磨を行った、４Ｈ型のポリタイプを有する２インチ（５０ｍｍ）のＳｉＣ単結晶基板のＳｉ面に、エピタキシャル成長を実施した。基板のオフ角は２°である。成長手順、温度等は、実施例１と同様であるが、ガス流量は、ＳｉＨ４流量を毎分４０ｃｍ３、Ｃ２Ｈ４流量を毎分２０ｃｍ３（Ｃ／Ｓｉ＝１．０）、ＨＣｌ流量を毎分４００ｃｍ３（Ｃｌ／Ｓｉ＝１０．０）にして、エピタキシャル層を１０μｍ成長した。成長後のエピタキシャル膜はステップ−バンチングの生じていない良好な膜であり、表面粗さのＲａ値は０．２６ｎｍであった。実施例１と同様に形成したショットキーバリアダイオードのｎ値は１．０２であり、この場合もほぼ理想的な特性が得られていることが分かった。また、前記と同様に、同基板上にショットキーバリアオードを更に１００個作製して同じ評価を行ったところ、全て不良なく同様の特性を示した。Example 4
Epitaxial growth was performed on the Si surface of a 2 inch (50 mm) SiC single crystal substrate having a 4H-type polytype, which was sliced, roughly ground, and normally polished in the same manner as in Example 1. The off angle of the substrate is 2 °. The growth procedure, temperature, and the like are the same as in Example 1, but the gas flow rate is 40 cm 3 per minute for the SiH 4 flow rate, 20 cm 3 per minute for the C 2 H 4 flow rate (C / Si = 1.0), HCl The flow rate was 400 cm 3 / min (Cl / Si = 10.0), and the epitaxial layer was grown to 10 μm. The grown epitaxial film was a good film with no step-bunching, and the Ra value of the surface roughness was 0.26 nm. The n value of the Schottky barrier diode formed in the same manner as in Example 1 was 1.02, and it was found that almost ideal characteristics were also obtained in this case. Similarly to the above, when 100 Schottky barrier anodes were further produced on the same substrate and subjected to the same evaluation, all showed the same characteristics without any defects.
（実施例５）
実施例１と同様にスライス、粗削り、通常研磨を行った、４Ｈ型のポリタイプを有する２インチ（５０ｍｍ）のＳｉＣ単結晶基板のＳｉ面に、エピタキシャル成長を実施した。基板のオフ角度は６°である。成長手順、温度等は、実施例１と同様であるが、ガス流量は、ＳｉＨ４流量を毎分４０ｃｍ３、Ｃ２Ｈ４流量を毎分２２ｃｍ３（Ｃ／Ｓｉ＝１．１）、ＨＣｌ流量を毎分２００ｃｍ３（Ｃｌ／Ｓｉ＝５．０）にして、エピタキシャル層を１０μｍ成長した。成長後のエピタキシャル膜はステップ−バンチングの生じていない良好な膜であり、表面粗さのＲａ値は０．１９ｎｍであった。このエピタキシャル膜と、従来の方法により形成した６°オフ基板上のエピタキシャル膜を用い、実施例２と同様にショットキーバリアダイオードの逆方向耐圧を５０個評価した。結果は、本発明によるエピタキシャル膜上のダイオードの耐圧（中央値）が３５０Ｖ、従来方法によるエピタキシャル膜（表面粗さのＲａ値：２ｎｍ）上のダイオードの耐圧（中央値）が３３０Ｖであり、本発明を用いたエピタキシャル膜上のダイオードの方が優れた特性を示していた。本発明によるエピタキシャル膜上に作製した１００個のダイオードは、全て不良ないものであった。従来方法によるエピタキシャル膜上に作製した１００個のダイオードの内、５個の不良が発生した。(Example 5)
Epitaxial growth was performed on the Si surface of a 2 inch (50 mm) SiC single crystal substrate having a 4H-type polytype, which was sliced, roughly ground, and normally polished in the same manner as in Example 1. The off angle of the substrate is 6 °. The growth procedure, temperature, etc. are the same as in Example 1, but the gas flow rate is 40 cm 3 per minute for the SiH 4 flow rate, 22 cm 3 per minute for the C 2 H 4 flow rate (C / Si = 1.1), HCl The epitaxial layer was grown to 10 μm at a flow rate of 200 cm 3 / min (Cl / Si = 5.0). The grown epitaxial film was a good film with no step-bunching, and the Ra value of the surface roughness was 0.19 nm. Using this epitaxial film and an epitaxial film on a 6 ° off substrate formed by a conventional method, 50 reverse breakdown voltages of Schottky barrier diodes were evaluated in the same manner as in Example 2. As a result, the withstand voltage (median value) of the diode on the epitaxial film according to the present invention is 350 V, and the withstand voltage (median value) of the diode on the epitaxial film (surface roughness Ra value: 2 nm) according to the conventional method is 330 V. The diode on the epitaxial film using the invention showed superior characteristics. All 100 diodes fabricated on the epitaxial film according to the present invention were not defective. Of the 100 diodes fabricated on the epitaxial film by the conventional method, 5 defects occurred.
（実施例６〜１７）
実施例１と同様にスライス、粗削り、通常研磨を行った、４Ｈ型のポリタイプを有する２インチ（５０ｍｍ）のＳｉＣ単結晶基板のＳｉ面に、エピタキシャル成長を実施した。成長手順、温度等は、実施例１と同様であり、基板のオフ角度、Ｃ／Ｓｉ比、Ｃｌ／Ｓｉ比を表１のように変えてエピタキシャル層を１０μｍ成長した。成長後のエピタキシャル膜はステップ−バンチングの生じていない良好な膜であり、表１には成長後のエピタキシャル膜表面粗さのＲａ値および実施例１と同様に形成したショットキーバリアダイオードのｎ値も示してある。Ｒａ値は全て０．４ｎｍ以下と、平坦性に優れた膜が得られていることが分かり、また、ｎ値も１．０３以下で、ほぼ理想的なダイオード特性が得られていた。なお、実施例１〜１７においては、成長前に塩化水素による基板のエッチングを行っているが、このプロセスを省略しても、成長後のＲａ値に変化は見られなかった。また、実施例６は、Ｒａ値が０．４ｎｍで、ｎ値が１．０３となっているが、基板のオフ角度が付いていないので、結晶成長速度が遅く、オフ角度が付いている基板を用いた場合に比べて１０μｍの厚さに成膜するのに長時間かかっている。(Examples 6 to 17)
Epitaxial growth was performed on the Si surface of a 2 inch (50 mm) SiC single crystal substrate having a 4H-type polytype, which was sliced, roughly ground, and normally polished in the same manner as in Example 1. The growth procedure, temperature, and the like were the same as in Example 1, and the epitaxial layer was grown to 10 μm with the substrate off-angle, C / Si ratio, and Cl / Si ratio changed as shown in Table 1. The grown epitaxial film is a good film with no step-bunching. Table 1 shows the Ra value of the surface roughness of the grown epitaxial film and the n value of the Schottky barrier diode formed in the same manner as in Example 1. Is also shown. It was found that Ra values were all 0.4 nm or less, and a film having excellent flatness was obtained. Also, an n value was 1.03 or less, and almost ideal diode characteristics were obtained. In Examples 1 to 17, the substrate was etched with hydrogen chloride before the growth. However, even if this process was omitted, the Ra value after the growth was not changed. In Example 6, the Ra value is 0.4 nm and the n value is 1.03. However, since the substrate has no off-angle, the crystal growth rate is low and the substrate has an off-angle. It takes a long time to form a film having a thickness of 10 μm as compared with the case of using the film.
（比較例）
比較例として、実施例１と同様にスライス、粗削り、通常研磨を行った、４Ｈ型のポリタイプを有する２インチ（５０ｍｍ）のＳｉＣ単結晶基板のＳｉ面に、エピタキシャル成長を実施した。基板のオフ角度は６°である。成長手順、温度等は、実施例１と同様であるが、ガス流量は、ＳｉＨ４流量を毎分４０ｃｍ３、Ｃ２Ｈ４流量を毎分２２ｃｍ３（Ｃ／Ｓｉ＝１．１）にして、ＨＣｌは流さずにエピタキシャル層を１０μｍ成長した。成長後のエピタキシャル膜の光学顕微鏡写真を図７に、表面ＡＦＭ像を図８に示す。図７、図８から、成長後の表面は皺状になっており、ステップ−バンチングが生じていることが分かる。また、図８から、表面粗さのＲａ値は１．９ｎｍであり、実施例１〜５に比べ、約一桁大きい値であった。実施例５の場合に示したように、このようなエピタキシャル膜上にショットキーバリアダイオードを形成し、逆方向の耐圧を評価したところ、本発明によるエピタキシャル膜上のダイオードに比べ、特性は劣っていた。同様に１００個のショットキーバリアダイオードを作製し、その内８個の不良が発生した。(Comparative example)
As a comparative example, epitaxial growth was performed on the Si surface of a 2 inch (50 mm) SiC single crystal substrate having a 4H-type polytype that was sliced, roughly cut, and normally polished as in Example 1. The off angle of the substrate is 6 °. The growth procedure, temperature, and the like are the same as in Example 1. However, the gas flow rate is 40 cm 3 per minute for the SiH 4 flow rate and 22 cm 3 per minute (C / Si = 1.1) for the C 2 H 4 flow rate. The epitaxial layer was grown to 10 μm without flowing HCl. An optical micrograph of the grown epitaxial film is shown in FIG. 7, and a surface AFM image is shown in FIG. 7 and 8, it can be seen that the surface after growth has a hook shape and step-bunching occurs. Further, from FIG. 8, the Ra value of the surface roughness is 1.9 nm, which is a value larger by about one digit than Examples 1-5. As shown in the case of Example 5, when a Schottky barrier diode was formed on such an epitaxial film and the reverse breakdown voltage was evaluated, the characteristics were inferior to those of the diode on the epitaxial film according to the present invention. It was. Similarly, 100 Schottky barrier diodes were produced, of which 8 defects occurred.
更に、基板のオフ角度が７°であるＳｉＣ単結晶基板を実施例１と同様に作製し、原料ガスと同時にＨＣｌを流した場合とＨＣｌを流さなかった場合について、実施例１と同様にエピタキシャル膜を成長させた。オフ角度が大きいのでステップ−バンチングがそもそも発生し難いので、ＨＣｌを添加しなくても成長表面が平坦であり、ＨＣｌを添加しても同じ平坦性を有する成長表面であった。 Further, a SiC single crystal substrate having a substrate off-angle of 7 ° was fabricated in the same manner as in Example 1, and the case where HCl was flowed simultaneously with the source gas and the case where HCl was not flowed were epitaxially formed as in Example 1. A film was grown. Since the off-angle is large, step-bunching hardly occurs in the first place. Therefore, the growth surface is flat without adding HCl, and the growth surface has the same flatness even when HCl is added.
また、実施例１における結晶成長時の温度は、１６００℃であるが、１５００℃及び１６５０℃でそれぞれ同様に結晶成長させたが、同じ結果を得ている。１４５０℃で実施例１と同様に結晶成長させたが、ショットキーバリアダイオードを作製すると不良発生率が大きくなった。また、１７００℃で実施例１と同様に結晶成長させたが、表面粗さのＲａ値が０．４を超えるものしか得られなかった。したがって、結晶性成長時の温度範囲は好ましくは、１５００〜１６５０℃とするとよい。 Moreover, although the temperature at the time of crystal growth in Example 1 was 1600 ° C., crystal growth was similarly performed at 1500 ° C. and 1650 ° C., respectively, but the same result was obtained. Crystal growth was carried out at 1450 ° C. in the same manner as in Example 1. However, when a Schottky barrier diode was manufactured, the defect occurrence rate increased. In addition, crystals were grown at 1700 ° C. in the same manner as in Example 1, but only those having an Ra value of surface roughness exceeding 0.4 were obtained. Therefore, the temperature range during crystal growth is preferably 1500 to 1650 ° C.
この発明によれば、ＳｉＣ単結晶基板上へのエピタキシャル成長において、ステップ−バンチングの少ない高品質エピタキシャル膜を有するエピタキシャルＳｉＣ単結晶基板を作成することが可能である。そのため、このような基板上に電子デバイスを形成すればデバイスの特性及び歩留まりが向上することが期待できる。本実施例においては、材料ガスとしてＳｉＨ４及びＣ２Ｈ４を用いているが、Ｓｉ源としてトリクロルシランを用い、Ｃ源としてＣ３Ｈ８等を用いた場合についても同様である。According to the present invention, it is possible to produce an epitaxial SiC single crystal substrate having a high-quality epitaxial film with less step-bunching in epitaxial growth on the SiC single crystal substrate. Therefore, if an electronic device is formed on such a substrate, it can be expected that the characteristics and yield of the device are improved. In this embodiment, SiH 4 and C 2 H 4 are used as the material gas, but the same applies to the case where trichlorosilane is used as the Si source and C 3 H 8 is used as the C source.
上記のように、従来技術で得られるオフ角度の小さいＳｉＣ基板、即ち、４°以下のオフ角度のＳｉＣ基板では、ステップ−バンチングの発生を抑えた高品質エピタキシャル膜が得られず、デバイス特性やデバイス歩留が十分でないという問題があることが明らかになってきた。 As described above, a SiC substrate with a small off-angle obtained by the conventional technology, that is, a SiC substrate with an off-angle of 4 ° or less cannot obtain a high-quality epitaxial film in which the occurrence of step-bunching is suppressed. It has become clear that there is a problem of insufficient device yield.
本発明は、オフ角度が４°乃至それ以下の基板を用いたエピタキシャル成長において、ステップ−バンチングの発生を抑えた高品質エピタキシャル膜を有するエピタキシャル単結晶基板及びその製造方法を提供することを目的とする。 The present invention, in the epitaxial growth using off angle of 4 ° or less of the substrate, step - aims to provide a epitaxial single crystal substrate and a manufacturing method thereof having high quality epitaxial films that suppresses the occurrence of bunching And
本発明は、エピタキシャル成長時に流す材料ガス（原料ガス）中に、特定の条件で塩化水素ガスを添加することで上記課題を解決できることを見出し、完成したものである。更に、前記方法により、ステップ−バンチングの発生が抑えられた結果、オフ角度が４°以下のＳｉＣ基板を用いたエピタキシャルＳｉＣ単結晶基板を作製できるようになり、該エピタキシャルＳｉＣ単結晶基板を用いてデバイス特性やデバイス歩留を詳細に検討した。オフ角度が４°以下のＳｉＣ基板を用いたエピタキシャルＳｉＣ単結晶基板で、炭化珪素単結晶薄膜表面が、表面粗さ（Ｒａ値）が０．５ｎｍ以下のものが得られていなかったので、該表面粗さレベルにおけるデバイス特性やデバイス歩留は知られていなかったが、本発明者らは、上記方法で作製したエビタキシャルＳｉＣ単結晶基板を用いて検討した結果、炭化珪素単結晶薄膜表面が、表面粗さ（Ｒａ値）が０．５ｎｍ以下であると、デバイス特性やデバイス歩留が顕著に向上することを見出した。 The present invention has been completed by finding that the above-mentioned problems can be solved by adding hydrogen chloride gas under specific conditions to a material gas (raw material gas) that flows during epitaxial growth. Furthermore, as a result of suppressing the occurrence of step-bunching by the above-described method, an epitaxial SiC single crystal substrate using a SiC substrate having an off angle of 4 ° or less can be produced, and the epitaxial SiC single crystal substrate is used. The device characteristics and device yield were examined in detail. In the epitaxial SiC single crystal substrate using the SiC substrate having an off angle of 4 ° or less, the surface of the silicon carbide single crystal thin film having a surface roughness (Ra value) of 0.5 nm or less was not obtained. Although device characteristics and device yield at the surface roughness level were not known, the present inventors examined using an epitaxial SiC single crystal substrate produced by the above method, and found that the surface of the silicon carbide single crystal thin film was It has been found that device characteristics and device yield are remarkably improved when the surface roughness (Ra value) is 0.5 nm or less.
即ち、本発明の要旨は次のとおりである。
（１）オフ角度が４°以下である炭化珪素単結晶基板上に炭化珪素単結晶薄膜を形成したエピタキシャル炭化珪素単結晶基板であって、前記炭化珪素単結晶薄膜表面の表面粗さ（Ｒａ値）が０．５ｎｍ以下であることを特徴とするエピタキシャル炭化珪素単結晶基板。
（２）オフ角度が４°以下である炭化珪素単結晶基板上に、熱化学蒸着法で炭化珪素単結晶薄膜をエピタキシャル成長させる際に、炭素と珪素を含む原料ガスを流すと同時に塩化水素ガスを流し、原料ガス中に含まれる炭素と珪素の原子数比（Ｃ／Ｓｉ比）が１．５以下であると共に、原料ガス中の珪素原子数に対する塩化水素ガス中の塩素原子数の比（Ｃｌ／Ｓｉ比）が１．０より大きく２０．０より小さくすることを特徴とするエピタキシャル炭化珪素単結晶基板の製造方法。
That is, the gist of the present invention is as follows.
(1) An epitaxial silicon carbide single crystal substrate in which a silicon carbide single crystal thin film is formed on a silicon carbide single crystal substrate having an off angle of 4 ° or less, and the surface roughness (Ra value) of the silicon carbide single crystal thin film surface ) Is 0.5 nm or less. Epitaxial silicon carbide single crystal substrate characterized by the above-mentioned.
(2) When a silicon carbide single crystal thin film is epitaxially grown by a thermal chemical vapor deposition method on a silicon carbide single crystal substrate having an off angle of 4 ° or less, a source gas containing carbon and silicon is flowed simultaneously with hydrogen chloride gas. The ratio of the number of atoms of carbon and silicon contained in the source gas (C / Si ratio) is 1.5 or less, and the ratio of the number of chlorine atoms in the hydrogen chloride gas to the number of silicon atoms in the source gas (Cl / Si ratio) is greater than 1.0 and less than 20.0. A method for producing an epitaxial silicon carbide single crystal substrate, wherein:
本発明によれば、基板のオフ角度が４°乃至それ以下であっても、ステップ−バンチングの発生を抑え、表面粗さのＲａ値の小さい高品質なエピタキシャル膜を有するＳｉＣ単結晶基板を提供することが可能である。 According to the present invention, there is provided an SiC single crystal substrate having a high-quality epitaxial film that suppresses the occurrence of step-bunching and has a small surface roughness Ra value even when the substrate off-angle is 4 ° or less. Is possible.
次に、本発明の内容を図１の成長シーケンスで説明する。ＳｉＣ単結晶基板をセットし、水素あるいは塩化水素中でのエッチングまでは、図６と同様である。その後、１５００〜１６００℃又は１５００〜１６５０℃の成長温度に上げ、材料ガスであるＳｉＨ４とＣ２Ｈ４を流して成長を開始するが、この時同時にＨＣｌガスも導入する。ＳｉＨ４流量は毎分４０〜５０ｃｍ３、Ｃ２Ｈ４流量は毎分２０〜４０ｃｍ３又は３０〜３０ｃｍ３であり、ＨＣｌの流量は、ガス中のＳｉとＣｌの原子数の比（Ｃｌ／Ｓｉ比）が１．０〜２０．０になるようにして、毎分４０〜１０００ｃｍ３程度が好ましい。成長速度はＨＣｌガスを流さない場合とほぼ同じであり、所望の膜厚が得られた時点でＳｉＨ４とＣ２Ｈ４及びＨＣｌの導入を止める。その後の手順は、ＨＣｌガスを流さない場合と同様である。このように、原料ガスとＨＣｌガスを同時に流すことにより、４°乃至それ以下という小さいオフ角を持った基板上であっても、表面のステップ−バンチングの発生が抑えられた良好なエピタキシャル膜が得られるようになる。 Next, contents of the present invention in growth sequence in Figure 1. The process up to the setting of the SiC single crystal substrate and the etching in hydrogen or hydrogen chloride is the same as in FIG. Thereafter, the growth temperature is increased to 1500 to 1600 ° C. or 1500 to 1650 ° C., and SiH 4 and C 2 H 4 which are material gases are supplied to start the growth. At this time, HCl gas is also introduced. SiH 4 flow rate per minute 40~50cm 3, C 2 H 4 flow rate per minute 20 to 40 cm 3 or 30～30Cm 3, the flow rate of the HCl, the ratio of the number of atoms of Si and Cl in the gas (Cl / The Si ratio is preferably about 1.0 to 20.0, and is preferably about 40 to 1000 cm 3 per minute. The growth rate is almost the same as when HCl gas is not flown, and the introduction of SiH 4 , C 2 H 4 and HCl is stopped when a desired film thickness is obtained. The subsequent procedure is the same as that when no HCl gas is flowed. In this way, by supplying the source gas and the HCl gas simultaneously, a good epitaxial film in which the generation of step-bunching on the surface is suppressed even on a substrate having a small off angle of 4 ° or less can be obtained. It will be obtained.
本発明により、４°乃至それ以下という小さいオフ角度（即ち、０°〜４°のオフ角度である。）を持った基板上であっても、表面のステップ−バンチングの発生が抑えられた良好なエピタキシャル膜が得られるようになったが、成長するエピタキシャル層の厚さについては、通常形成されるデバイスの耐圧、エピタキシャル膜の生産性等を考慮した場合、５μｍ以上５０μｍ以下が好ましい。また、オフ角度が０°超でオフ角度を有する基板がエピタキシャル膜の成長し易さの点から好ましい。さらに、基板のオフ角度については、１°以下であると、表面に存在するステップの数が少なくなり、本発明の効果が現れ難くなるため、１°より大きく４°以下が好ましい。また、成長時のガス中に含まれるＣｌ／Ｓｉ比は、１．０より小さいとＨＣｌガスを添加した効果が現れず、２０．０より大きいとＨＣｌガスによるエッチングが行われて来るため、１．０から２０．０の間が望ましいが、より好適には４．０〜１０．０の間である。更に好ましいＣｌ／Ｓｉ比は、４．０以上１０．０未満である。 According to the present invention, even on a substrate having a small off angle of 4 ° or less (that is, an off angle of 0 ° to 4 °), the generation of surface step-bunching is suppressed. An epitaxial film can be obtained, but the thickness of the grown epitaxial layer is preferably 5 μm or more and 50 μm or less in consideration of the breakdown voltage of a normally formed device, the productivity of the epitaxial film, and the like. Further, a substrate having an off angle exceeding 0 ° and an off angle is preferable from the viewpoint of easy growth of the epitaxial film. Further, the off angle of the substrate, if it is 1 ° or less, the number of steps on the surface is reduced, the effect of the present invention is less likely to appear, preferably 1 ° greater than 4 ° or less. Further, if the Cl / Si ratio contained in the gas during growth is smaller than 1.0, the effect of adding HCl gas does not appear, and if it is larger than 20.0, etching with HCl gas is performed. It is preferably between 0.0 and 20.0, but more preferably between 4.0 and 10.0. A more preferable Cl / Si ratio is 4.0 or more and less than 10.0.
さらに、材料ガスにおけるＣ／Ｓｉ比は、ステップ−フロー成長を促進するため１．５以下であるが、１．０より小さいと、所謂サイト−コンペティション（site-competition）効果で、残留窒素の取り込みが大きくなり、エピタキシャル膜の純度が下がるため、より好適には１．０〜１．５の間である。 Furthermore, the C / Si ratio in the material gas is 1.5 or less in order to promote step-flow growth, but if it is less than 1.0, the so-called site-competition effect causes the incorporation of residual nitrogen. Is increased, and the purity of the epitaxial film is lowered. Therefore, it is more preferably between 1.0 and 1.5.
また、本発明では、オフ角度が４°以下であるＳｉＣ基板は、直径２インチ以上（直径５０ｍｍ以上）のサイズである方が、本発明の効果がより顕著に得られる。ＳｉＣ基板が小さい場合（例えば、直径２インチ（直径５０ｍｍ）未満では）、熱ＣＶＤ法における基板の加熱は全基板表面に均一に行うことが容易であり、その結果、ステップ−バンチングの発生が起きにくい。 Further, in the present invention, the effect of the present invention is more remarkably obtained when the SiC substrate having an off angle of 4 ° or less is 2 inches or more in diameter (50 mm or more in diameter). When the SiC substrate is small (for example, less than 2 inches in diameter (diameter 50 mm)), it is easy to heat the substrate in the thermal CVD method uniformly over the entire substrate surface, and as a result, step-bunching occurs. Hateful.
（実施例６〜１７）
実施例１と同様にスライス、粗削り、通常研磨を行った、４Ｈ型のポリタイプを有する２インチ（５０ｍｍ）のＳｉＣ単結晶基板のＳｉ面に、エピタキシャル成長を実施した。成長手順、温度等は、実施例１と同様であり、基板のオフ角度、Ｃ／Ｓｉ比、Ｃｉ／Ｓｉ比を表１のように変えてエピタキシャル層を１０μｍ成長した。成長後のエピタキシャル膜はステップ−バンチングの生じていない良好な膜であり、表１には成長後のエピタキシャル膜表面粗さのＲａ値および実施例１と同様に形成したショットキーバリアダイオードのｎ値も示してある。Ｒａ値は全て０．５ｎｍ以下と、平坦性に優れた膜が得られていることが分かり、また、ｎ値も１．０３以下で、ほぼ理想的なダイオード特性が得られていた。なお、実施例１〜１７においては、成長前に塩化水素による基板のエッチングを行っているが、このプロセスを省略しても、成長後のＲａ値に変化は見られなかった。また、実施例６は、Ｒａ値が０．５ｎｍで、ｎ値が１．０３となっているが、基板のオフ角度が付いていないので、結晶成長速度が遅く、オフ角度が付いている基板を用いた場合に比べて１０μｍの厚さに成膜するのに長時間かかっている。
(Examples 6 to 17)
Epitaxial growth was performed on the Si surface of a 2 inch (50 mm) SiC single crystal substrate having a 4H-type polytype, which was sliced, roughly ground, and normally polished in the same manner as in Example 1. The growth procedure, temperature, and the like were the same as in Example 1, and the epitaxial layer was grown to 10 μm while changing the off angle, C / Si ratio, and Ci / Si ratio of the substrate as shown in Table 1. The grown epitaxial film is a good film with no step-bunching. Table 1 shows the Ra value of the surface roughness of the grown epitaxial film and the n value of the Schottky barrier diode formed in the same manner as in Example 1. Is also shown. Ra values are all 0. It was found that a film excellent in flatness was obtained at 5 nm or less, and the n value was 1.03 or less, and almost ideal diode characteristics were obtained. In Examples 1 to 17, the substrate was etched with hydrogen chloride before the growth. However, even if this process was omitted, the Ra value after the growth was not changed. In Example 6, the Ra value is 0. 0. Although the n value is 1.03 at 5 nm, since the substrate has no off-angle, the crystal growth rate is slow, and the thickness is 10 μm compared to the case of using a substrate with an off-angle. It takes a long time to form a film.
本発明は、エピタキシャル成長時に流す材料ガス（原料ガス）中に、特定の条件で塩化水素ガスを添加することで上記課題を解決できることを見出し、完成したものである。更に、前記方法により、ステップ−バンチングの発生が抑えられた結果、オフ角度が４°以下のＳｉＣ基板を用いたエピタキシャルＳｉＣ単結晶基板を作製できるようになり、該エピタキシャルＳｉＣ単結晶基板を用いてデバイス特性やデバイス歩留を詳細に検討した。オフ角度が４°以下のＳｉＣ基板を用いたエピタキシャルＳｉＣ単結晶基板で、炭化珪素単結晶薄膜表面が、エピタキシャル成長後の表面粗さ（Ｒａ値）が０．５ｎｍ以下のものが得られていなかったので、該表面粗さレベルにおけるデバイス特性やデバイス歩留は知られていなかったが、本発明者らは、上記方法で作製したエビタキシャルＳｉＣ単結晶基板を用いて検討した結果、炭化珪素単結晶薄膜表面が、エピタキシャル成長後の表面粗さ（Ｒａ値）が０．５ｎｍ以下であると、デバイス特性やデバイス歩留が顕著に向上することを見出した。 The present invention has been completed by finding that the above-mentioned problems can be solved by adding hydrogen chloride gas under specific conditions to a material gas (raw material gas) that flows during epitaxial growth. Further, as a result of suppressing the occurrence of step-bunching by the above method, an epitaxial SiC single crystal substrate using an SiC substrate having an off angle of 4 ° or less can be produced. Using the epitaxial SiC single crystal substrate, The device characteristics and device yield were examined in detail. An epitaxial SiC single crystal substrate using an SiC substrate having an off angle of 4 ° or less, and a silicon carbide single crystal thin film surface having a surface roughness (Ra value) after epitaxial growth of 0.5 nm or less was not obtained. Therefore, although the device characteristics and device yield at the surface roughness level were not known, the present inventors investigated using an epitaxial SiC single crystal substrate produced by the above method, and as a result, It has been found that when the surface roughness (Ra value) after epitaxial growth of the thin film surface is 0.5 nm or less, device characteristics and device yield are remarkably improved.
即ち、本発明の要旨は次のとおりである。
（１）オフ角度が４°以下である炭化珪素単結晶基板上に炭化珪素単結晶薄膜を形成したステップ−バンチングの発生を抑制するエピタキシャル炭化珪素単結晶基板であって、前記炭化珪素単結晶薄膜表面のエピタキシャル成長後の表面粗さ（Ｒａ値）が０．５ｎｍ以下であることを特徴とするエピタキシャル炭化珪素単結晶基板。
（２）オフ角度が４°以下である炭化珪素単結晶基板上に、熱化学蒸着法で炭化珪素単結晶薄膜をエピタキシャル成長させる際に、炭素と珪素を含む原料ガスを流すと同時に塩化水素ガスを流し、原料ガス中に含まれる炭素と珪素の原子数比（Ｃ／Ｓｉ比）が１．５以下であると共に、原料ガス中の珪素原子数に対する塩化水素ガス中の塩素原子数の比（Ｃｌ／Ｓｉ比）が１．０より大きく２０．０より小さくすることを特徴とするエピタキシャル炭化珪素単結晶基板の製造方法。
That is, the gist of the present invention is as follows.
(1) An epitaxial silicon carbide single crystal substrate that suppresses generation of step-bunching in which a silicon carbide single crystal thin film is formed on a silicon carbide single crystal substrate having an off angle of 4 ° or less, and the silicon carbide single crystal thin film An epitaxial silicon carbide single crystal substrate, wherein the surface roughness (Ra value) after epitaxial growth of the surface is 0.5 nm or less.
(2) When a silicon carbide single crystal thin film is epitaxially grown on a silicon carbide single crystal substrate having an off angle of 4 ° or less by a thermal chemical vapor deposition method, a source gas containing carbon and silicon is allowed to flow simultaneously with hydrogen chloride gas. The ratio of the number of atoms of carbon and silicon contained in the source gas (C / Si ratio) is 1.5 or less, and the ratio of the number of chlorine atoms in the hydrogen chloride gas to the number of silicon atoms in the source gas (Cl / Si ratio) is greater than 1.0 and less than 20.0. A method for producing an epitaxial silicon carbide single crystal substrate, wherein:
本発明によれば、基板のオフ角度が４°乃至それ以下であっても、ステップ−バンチングの発生を抑え、エピタキシャル成長後の表面粗さのＲａ値の小さい高品質なエピタキシャル膜を有するＳｉＣ単結晶基板を提供することが可能である。 According to the present invention, even if the substrate off-angle is 4 ° or less, the SiC single crystal having a high-quality epitaxial film that suppresses the occurrence of step-bunching and has a small surface roughness Ra value after epitaxial growth. It is possible to provide a substrate.
そして、本発明によれば、ＳｉＣ単結晶基板にエピタキシャル膜を成長する際に所定の流量のＨＣｌガスを存在させることにより、エピタキシャル成長後の表面粗さ（Ｒａ値）が０．５ｎｍ以下といった高品質のＳｉＣ単結晶薄膜を得ることができる。尚、表面粗さＲａはＪＩＳ Ｂ０６０１：２００１に準拠する算術平均粗さである。本発明の製造方法においてより最適な条件とすれば、表面粗（Ｒａ値）が０．４ｎｍ以下の更に高品質のＳｉＣ単結晶薄膜を容易に得ることができる。 According to the present invention, when an epitaxial film is grown on an SiC single crystal substrate, HCl gas at a predetermined flow rate is allowed to exist so that the surface roughness (Ra value) after epitaxial growth is as high as 0.5 nm or less. SiC single crystal thin film can be obtained. The surface roughness Ra is an arithmetic average roughness based on JIS B0601: 2001. If the conditions are more optimal in the production method of the present invention, a higher quality SiC single crystal thin film having a surface roughness (Ra value) of 0.4 nm or less can be easily obtained.
更に、本発明によって、エピタキシャル成長後の表面粗さ（Ｒａ値）が０．５ｎｍ以下を含む表面粗さの異なる種々のエピタキシャル膜を有するＳｉＣ単結晶基板を作製し、それぞれのデバイス特性やデバイス歩留を調べた。その結果、下記の実施例にも示すように、ＳｉＣ単結晶薄膜表面が、エピタキシャル成長後の表面粗さ（Ｒａ値）が０．５ｎｍ以下、好ましくは０．４ｎｍ以下であると、デバイス特性やデバイス歩留が顕著に向上することを見出した。 Furthermore, according to the present invention, SiC single crystal substrates having various epitaxial films with different surface roughnesses including a surface roughness (Ra value) after epitaxial growth of 0.5 nm or less are prepared, and the respective device characteristics and device yields are produced. I investigated. As a result, as shown in the following examples, when the surface of the SiC single crystal thin film has a surface roughness (Ra value) after epitaxial growth of 0.5 nm or less, preferably 0.4 nm or less, device characteristics and devices We found that the yield was significantly improved.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016096247A (en) * | 2014-11-14 | 2016-05-26 | 株式会社デンソー | Semiconductor substrate and manufacturing method of the same |
Families Citing this family (40)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012004269A (en) * | 2010-06-16 | 2012-01-05 | Sumitomo Electric Ind Ltd | Method of manufacturing silicon carbide semiconductor device and apparatus of manufacturing silicon carbide semiconductor device |
| JP5678622B2 (en) * | 2010-12-03 | 2015-03-04 | 株式会社デンソー | Method for producing silicon carbide single crystal |
| JP5778945B2 (en) * | 2011-02-24 | 2015-09-16 | 株式会社東芝 | Associative memory |
| DE112011105073T5 (en) * | 2011-03-22 | 2013-12-24 | Sumitomo Electric Industries, Ltd. | silicon carbide substrate |
| WO2013036376A2 (en) * | 2011-09-10 | 2013-03-14 | Semisouth Laboratories, Inc. | Methods for the epitaxial growth of silicon carbide |
| US9165768B2 (en) | 2011-12-16 | 2015-10-20 | Lg Innotek Co., Ltd. | Method for deposition of silicon carbide and silicon carbide epitaxial wafer |
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| KR101926694B1 (en) * | 2012-05-30 | 2018-12-07 | 엘지이노텍 주식회사 | Silicon carbide epi wafer and method of fabricating the same |
| KR101976600B1 (en) * | 2012-06-28 | 2019-05-09 | 엘지이노텍 주식회사 | Silicon carbide epi wafer and method of fabricating the same |
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| US9797064B2 (en) | 2013-02-05 | 2017-10-24 | Dow Corning Corporation | Method for growing a SiC crystal by vapor deposition onto a seed crystal provided on a support shelf which permits thermal expansion |
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| CN103715069B (en) * | 2013-12-02 | 2016-09-21 | 中国电子科技集团公司第五十五研究所 | A kind of reduce the method for defect in silicon carbide epitaxial film |
| JP6304699B2 (en) * | 2014-07-16 | 2018-04-04 | 昭和電工株式会社 | Method for manufacturing epitaxial silicon carbide wafer |
| US9279192B2 (en) | 2014-07-29 | 2016-03-08 | Dow Corning Corporation | Method for manufacturing SiC wafer fit for integration with power device manufacturing technology |
| US10030319B2 (en) * | 2014-11-27 | 2018-07-24 | Sumitomo Electric Industries, Ltd. | Silicon carbide substrate, method for producing same, and method for manufacturing silicon carbide semiconductor device |
| WO2016140051A1 (en) | 2015-03-03 | 2016-09-09 | 昭和電工株式会社 | Sic epitaxial wafer and method for manufacturing sic epitaxial wafer |
| CN104810248B (en) * | 2015-04-08 | 2017-08-08 | 中国电子科技集团公司第五十五研究所 | Suitable for the in-situ treatment method of 4 ° and 8 ° off-axis silicon face silicon carbide substrates |
| CN104779141A (en) * | 2015-04-16 | 2015-07-15 | 中国科学院半导体研究所 | Preparation method of low-deflection angle silicon carbide homogeneous epitaxial material |
| CN105826186B (en) * | 2015-11-12 | 2018-07-10 | 中国电子科技集团公司第五十五研究所 | The growing method of great surface quality silicon carbide epitaxial layers |
| JP6579710B2 (en) | 2015-12-24 | 2019-09-25 | 昭和電工株式会社 | Method for manufacturing SiC epitaxial wafer |
| CN107068539B (en) * | 2016-12-15 | 2019-11-22 | 中国电子科技集团公司第五十五研究所 | The method for reducing silicon carbide epitaxy base plane dislocation density |
| KR101951838B1 (en) * | 2016-12-23 | 2019-02-26 | 주식회사 포스코 | method for fabricating Silicon carbide epitaxial wafer |
| EP4261870A1 (en) * | 2020-12-14 | 2023-10-18 | NuFlare Technology, Inc. | Vapor-phase growth apparatus and vapor-phase growth method |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000001398A (en) * | 1998-06-09 | 2000-01-07 | Fuji Electric Co Ltd | Production of silicon carbide semiconductor substrate |
| JP2005093477A (en) * | 2003-09-12 | 2005-04-07 | Shikusuon:Kk | Method for cvd epitaxial growth |
| JP2006321696A (en) * | 2005-05-20 | 2006-11-30 | Hitachi Cable Ltd | Method for manufacturing silicon carbide single crystal |
| JP2006321707A (en) * | 2005-04-22 | 2006-11-30 | Bridgestone Corp | Silicon carbide single crystal wafer and process for producing the same |
| JP2006328455A (en) * | 2005-05-24 | 2006-12-07 | Nippon Steel Corp | Epitaxial silicon carbide single crystal substrate, and its manufacturing method |
| JP2007131504A (en) * | 2005-11-14 | 2007-05-31 | Shikusuon:Kk | SiC EPITAXIAL WAFER AND SEMICONDUCTOR DEVICE USING THE SAME |
| JP2008222509A (en) * | 2007-03-14 | 2008-09-25 | Matsushita Electric Ind Co Ltd | METHOD FOR PRODUCING SINGLE CRYSTAL SUBSTRATE WITH SiC EPITAXIAL FILM |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5216531B2 (en) | 1972-08-14 | 1977-05-10 | ||
| JPH02157196A (en) | 1988-12-08 | 1990-06-15 | Nec Corp | Method for growing semiconductor crystal |
| JP2633403B2 (en) | 1990-03-26 | 1997-07-23 | シャープ株式会社 | Method for producing silicon carbide single crystal |
| EP0962963A4 (en) * | 1997-08-27 | 2004-08-04 | Matsushita Electric Ind Co Ltd | Silicon carbide substrate, process for producing the same, and semiconductor element containing silicon carbide substrate |
| US6734461B1 (en) * | 1999-09-07 | 2004-05-11 | Sixon Inc. | SiC wafer, SiC semiconductor device, and production method of SiC wafer |
| WO2003085175A1 (en) * | 2002-04-04 | 2003-10-16 | Nippon Steel Corporation | Seed crystal of silicon carbide single crystal and method for producing ingot using same |
| WO2005093796A1 (en) * | 2004-03-26 | 2005-10-06 | The Kansai Electric Power Co., Inc. | Bipolar semiconductor device and process for producing the same |
| JP4427472B2 (en) | 2005-03-18 | 2010-03-10 | 新日本製鐵株式会社 | Method for manufacturing SiC single crystal substrate |
| JP4954654B2 (en) | 2006-09-21 | 2012-06-20 | 新日本製鐵株式会社 | Epitaxial silicon carbide single crystal substrate and manufacturing method thereof |
-
2010
- 2010-01-29 EP EP10735972.1A patent/EP2395133B1/en active Active
- 2010-01-29 CN CN201080005900.5A patent/CN102301043B/en active Active
- 2010-01-29 KR KR1020117013379A patent/KR101333337B1/en active IP Right Grant
- 2010-01-29 JP JP2010523229A patent/JP4719314B2/en active Active
- 2010-01-29 US US13/138,270 patent/US20110278596A1/en not_active Abandoned
- 2010-01-29 WO PCT/JP2010/051655 patent/WO2010087518A1/en active Application Filing
-
2014
- 2014-11-19 US US14/547,838 patent/US20150075422A1/en not_active Abandoned
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000001398A (en) * | 1998-06-09 | 2000-01-07 | Fuji Electric Co Ltd | Production of silicon carbide semiconductor substrate |
| JP2005093477A (en) * | 2003-09-12 | 2005-04-07 | Shikusuon:Kk | Method for cvd epitaxial growth |
| JP2006321707A (en) * | 2005-04-22 | 2006-11-30 | Bridgestone Corp | Silicon carbide single crystal wafer and process for producing the same |
| JP2006321696A (en) * | 2005-05-20 | 2006-11-30 | Hitachi Cable Ltd | Method for manufacturing silicon carbide single crystal |
| JP2006328455A (en) * | 2005-05-24 | 2006-12-07 | Nippon Steel Corp | Epitaxial silicon carbide single crystal substrate, and its manufacturing method |
| JP2007131504A (en) * | 2005-11-14 | 2007-05-31 | Shikusuon:Kk | SiC EPITAXIAL WAFER AND SEMICONDUCTOR DEVICE USING THE SAME |
| JP2008222509A (en) * | 2007-03-14 | 2008-09-25 | Matsushita Electric Ind Co Ltd | METHOD FOR PRODUCING SINGLE CRYSTAL SUBSTRATE WITH SiC EPITAXIAL FILM |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016096247A (en) * | 2014-11-14 | 2016-05-26 | 株式会社デンソー | Semiconductor substrate and manufacturing method of the same |
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